A POS (“Point of Sale”) system is a typical merchandise management system in a store. In the current POS system, when an item is sold, i.e., when payment is completed, sales information thereof is recorded in a database for the first time. Therefore, for example, when an item is in a shopping basket before payment, this leads to a situation in which the item is not on a store shelf although the item is supposed to be in stock.
In this regard, for example, in a disclosed merchandise management system, a reader/writer is attached to a shopping basket itself to manage a tagged item in the shopping basket before payment (see, e.g., Patent Document 1). This system can also manage items remaining in a store.
Patent Document 1: Japanese Laid-Open Patent Publication No. 2004-292143.
However, in the configuration described above, if items placed in a shopping basket are stacked (tags are stacked), or an item or a package contains metal, radiation characteristics of an antenna are degraded in each tag, which makes it difficult to read a tagged item in the shopping basket.